100215 07:02:24  mysqld started
/usr/libexec/mysqld: Can't read dir of '/tmp/' (Errcode: 13)
/usr/libexec/mysqld: Can't create/write to file '/tmp/ibyP1qUC' (Errcode: 13)
100215  7:02:24  InnoDB: Error: unable to create temporary file; errno: 13
100215  7:02:24 [ERROR] Can't init databases
100215  7:02:24 [ERROR] Aborting

100215  7:02:24 [Note] /usr/libexec/mysqld: Shutdown complete

100215 07:02:24  mysqld ended

One of my servers was rebooted for some reason and all sites and e-mail accounts were down because the database could not be connected.  The first thing I checked was mysqld of course and it was not running.  The above was revealed in /var/log/mysqld.log

I was starting to panic and wondered if the server was compromised and I even checked /var/lib/mysql to make sure all the database data was still there.

The solution for this MySQL Error is simple:

chown root.root /tmp


chmod 1777 /tmp

And of course be sure that you start MySQL again.